Devices operating on the ultrasonic principle have been used for quite some time especially in dentistry where they are useful for removal of tartar from the teeth. In such devices, nickel rods or ferrites are used to generate vibrations of ultrasonic frequency usually in the range of 20-30 kHz. These vibrations are used to drive the work tool that loosens the tartar from the teeth.
A known type of piezoelectric dental cleaning device has a piezoelectric vibrator element in the shape of a cylindrical tube which occupies almost the entire casing of the hand tool. The oscillator for exciting the piezoelectric vibrator element is a separate external unit which is connected with the vibrator element by a shielded cable capable of transmitting high frequencies.
The known devices are relatively large and heavy and what is most important take up considerable room which is particularly inconvenient in view of the notorious shortage of space around a dentist's chair. The generator or oscillator together with its power supply and controls especially those for tuning and volume control were housed in a relatively bulky case or container which due to a lack of space could not be accommodated at the usual dentist's chair. One solution was to install the oscillator with its power supply and controls in a separate cabinet at one side of the room with a relatively long shielded cable extending from the oscillator to the hand held tool containing the piezoelectric vibrator element. Another solution was to install the tartar remover at a separate chair so that the dentist could have the switch and manual controls of the oscillator more conveniently located. However, this entailed the expense of an additional chair and room to accommodate it and was also inconvenient for a patient requiring regular dental work and tartar removal since it meant that he would have to change chairs.